基于DEM的山地丘陵区土地利用/覆被研究——以青海湖流域为例

研究地形对土地利用空间分布格局的影响,对探讨不同地貌部位自然因素和人文因素在土地利用变化过程中的作用具有重要意义。论文以青海湖流域为例,对比各土地利用类型的投影面积与地表真实面积的差异,并从地形(高程、坡度、坡向)角度分析了流域内土地利用的空间分布格局。结果表明:流域投影面积与地表真实面积相差754.79 km²。耕地、居民地、水域、沙地主要分布在3 500 m以下,且坡度小于2°的平地上,耕地和居民地多分布在南坡和西南坡上;林地主要分布在3 500~4 000 m且坡度多在6~25°的缓地和斜坡上,各坡向分布较均匀;草地主要分布在4 500 m以下且坡度小于25°的坡地上;沼泽多分布在3 500~4 500 m且坡度小于25°的河源地区,多分布在北坡和东北坡上;其它用地主要分布在4 000~4 500 m的坡度较大的斜坡或陡坡上。随高度、坡度增加,土地利用程度综合指数呈下降趋势;土地利用综合指数在坡向上呈现:平地＞阳坡＞阴坡。说明地形在很大程度上影响着青海湖流域的土地利用分布,且这种影响比较符合当地的自然规律和社会经济规律。

Study on Land Use/Cover in Mountain Area Based on the DEM -Taking the Qinghai Lake Basin as an Example

Study on the influence of terrain upon land use pattern is necessary. This would help us to have a better understanding of the effects of human activity and the physical geography on the processes of land use/cover change, and is of practical significance in regional development and environmental protection. Based on the 1 ∶50000 DEM (Digital Elevation Model) and the multi-temporal remote sensing data of TM image extracted in 2004, this study, taking the Qinghai Lake Basin as an example, analyzed the difference between projected area and true surface area and the relationship between the terrain (elevation, slope and aspect) and the spatial distribution pattern of land use/cover. The conclusions of the study can be drawn as follows: 1) The true surface area is larger than projected area by 754.79 km². 2) There were different land use types associated with different elevations, slope gradients and aspects. The main distributions of different land use types are listed as: cropland, habitation, water area and sandy land (below 3500 m and 2°, S and S-W aspects), woodland (3500-4000 m and 6°-25°), grassland (below 4500 m and 25°), swamp (3500-4500 m, below 25°, N and N-E aspects) and unused land (4000-4500 m, above 15°). 3) With the rise of elevation and slope, the index of land use intensity showed a gradual decreasing tendency, and the index of land use intensity decreased in the order of flat land, sunny slope and shady slope. These also showed that the terrain features are the foundation of regional land use pattern in the Qinghai Lake Basin. The reason was the terrain factor determines the redistribution of rainfall, heat and other natural resource, which finally affect the land use type and degree of human being. Compared the index of land use intensity with other typical regions, human activity had little effect on the land use/cover in this study area, so the related researches on environmental and ecological problems should pay more attention to the natural driving factors.